Any major legislation will have obstacles and roadblocks, and in the case of tax reform likely some near-fatal experiences. The media has focused on differences between the Ways and Means (W&M) Committee tax legislation and Senate Finance Committee (SFC) Chairman Hatch’s initial proposal, namely differences in the treatment of state and local property tax deductions and a one-year delay in the corporate 20% tax rate.

Those differences are relatively minor in the Republican Party’s desperate desire to have one major legislative victory before the 2018 elections. Below are five more significant issues that could determine the fate and timing of federal tax reform in 2017 or 2018.

Deficit increases not offset significantly by economic growth. The $1.5 trillion increase in deficit is a concern of several Republican senators, given low current unemployment and large future deficits from baby boomers’ retirement and health programs. When JCT and CBO complete their dynamic fiscal estimate, it may show only a small reduction in the estimated static deficit. This may be why the House will vote even before the dynamic score is finished.

Byrd rule preventing long-term deficits. Senate rules don’t allow a majority vote if legislation increases the deficit beyond 2027. This required the Bush 2001 tax cuts to be sunset after 10 years. The SFC Chairman’s mark has large deficits in 2027, so the Chairman’s mark will need to be changed drastically to comply with the Byrd rule. Sun-setting corporate tax cuts will make the dynamic effects even weaker, and make the proposal less attractive to many.

Business tax cuts may be whittled away as they try to make the package more appealing to households. During the W&M Committee legislative changes, Republicans increased deemed repatriation tax rates and retightened the related party payment rule to reduce the business tax cut to provide more household tax cuts. At some point, more of the business community might say it is not beneficial to their industry.

Refundable tax credits. Several Republican Senators are not supporters of refundable tax credits (low-income “welfare” through the tax code, rather than corporate welfare). Much of the tax reduction for some low and middle-income families is due to larger refundable tax credits. With a narrow margin to get 50 Republicans, this could be the tipping issue for at least one Republican senator.

There will be other obstacles raised and pre-mature death warnings as the legislation goes through the SFC, the House and Senate, and a conference committee. Still I predict legislation called tax “reform” will be enacted in early spring of 2018, although scaled back to a smaller version with more of the tax cuts going to non-business households. Stay tuned.